1. Field
The field relates to an organic light emitting display device and a method of manufacturing the same, and further to an organic light emitting display device having a bottom emission structure and a method of manufacturing the same.
2. Description of the Related Technology
Organic light emitting elements emit light when holes injected from an anode electrode and electrons injected from a cathode electrode recombine in an organic light emitting layer. The holes and electrons are injected by applying a voltage difference across the anode electrode and the cathode electrode.
Since such organic light emitting elements have a self-emission feature, organic light emitting display devices can be manufactured to have a bottom emission structure in which emitted light travels to a substrate with a thin film transistor and a top emission structure in which light travels to over a thin film transistor.
Since light travels to the substrate with a thin film transistor in the bottom emission structure, the line connected to the thin film transistor is excepted from the display region, whereas since light travels over the thin film transistor in the top emission structure, a relatively wide display region can be ensured.
Nevertheless, organic light emitting display devices having a top emission structure requires more masks in the manufacturing process than those having the bottom emission structure, such that use of the bottom emission structure has been recently increased in consideration of reducing the manufacturing cost.
However, in the bottom emission structure, since the anode electrode made of a transparent electrode material is disposed adjacent to the surface of the substrate, the surface of the anode electrode under an upper layer is damaged by plasma etc., in etching the upper layer. When transparent electrode materials, such as ITO and IZO, are exposed to plasma, the indium (In) on the surface is removed and conductivity and transmittance are correspondingly reduced, and as a result, the light emission characteristics are reduced. Further, the surface roughness increases, which may causes defective products in the manufacturing process.